Is the leak coming from the hose end?
You didn't mention whether you changed the hoses out with German made hoses or ones from NAPA or the like. If you look as the car is running, is the leak from the neck or from the hose end? If from the neck I would pull the hose and check for either corrosion build up or a rough spot on the area. If it's leaking from the end of the hose , or the hose rubber, than the hose is at fault. I'd also look at the angle that the hose is at before tightening the clamp. If it's not at a perpendicular angle all the way around the neck area, then you are leaving a space in the hose where it's not making good contact with neck as you tighten it down.
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'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan